This disclosure relates to a computer program. More particularly, this disclosure relates to a computer program that causes a computer to function so as to direct the line of sight of a user who is wearing a head-mounted display (hereinafter abbreviated as “HMD”) on his/her head and is immersed in a three-dimensional virtual space toward a given direction in the three-dimensional virtual space.
A known HMD includes a type that is capable of presenting a three-dimensional virtual space image with a display or the like worn on the head of a user and positioned at the user's eye level. In particular, HMDs capable of displaying a 360-degree panoramic image in a three-dimensional virtual space are known. An HMD usually includes various sensors (for example, an acceleration sensor and an angular velocity sensor) to obtain posture data by measuring the posture of the main body of the user wearing the HMD. The HMD particularly measures the rotation angle of the user's head so that the direction of the line of sight on the panoramic image can be changed based on the information about the rotation angle. Specifically, when the user wearing the HMD tilts and turns his/her head, the HMD makes the direction of the line of sight on the 360-degree panoramic image change accordingly. The user immersed in the three-dimensional virtual space can cast his/her line of sight freely to any direction within the three-dimensional space by the movement of his/her head.
HMDs thus heighten the user's sense of immersion in the visual world and improve the level of entertainment. On the other hand, HMDs have difficulty with directing the user's line of sight in a scene where the developer wants the user to cast his/her line of sight to a particular point in the three-dimensional virtual space.
In Japanese Patent Application Laid-open No. Hei 11-265462, there is disclosed the related art that recommends a viewpoint to the user. Specifically, recommended vector information is set which specifies a viewpoint on an object image in a three-dimensional space that is to be recommended, and viewpoint information that is used to display the object image is determined based on the recommended vector information. The object image is thus displayed in a manner that reflects the intent of a person who has set the recommended vector information (Paragraph [0008]). A visual part (an arrow, a circle, or the like) is applicable here as a recommended vector (Paragraph [0033]). However, the disclosure of Japanese Patent Application Laid-open No. Hei 11-265462 is not directly related to the movement of a user's head wearing an HMD that is described above.